1. Field of the Invention
This invention relates to a floppy disk drive, and in particular to a structure of a frame and a casing of a floppy disk drive, in which the casing includes upper and lower covers for covering the frame.
2. Description of the Prior Art
As is well known, a floppy disk drive (hereinafter, simply referred to as a “disk drive” on occasions) is an apparatus for writing and reading data to and from a floppy disk which is a disk-shaped magnetic recording medium housed in a predetermined cartridge. Such a floppy disk drive is mounted in laptop personal computers, notebook personal computers or notebook word processors or the like.
Generally, such a floppy disk drive includes magnetic heads for writing and reading data to and from a floppy disk, a carriage assembly on which the magnetic heads are provided for allowing the magnetic heads to be moved with respect to the floppy disk along a radial direction thereof, a stepping motor for moving the carriage assembly along the radial direction of the floppy disk, and a spindle motor for rotationally driving the floppy disk.
Hereinbelow, based on FIG. 9 to FIG. 12, a description will be made with regard to a floppy disk drive for a 3.5 inch floppy disk which has a conventional structure of a frame and a casing which includes upper and lower covers for covering the frame. FIG. 9 is an exploded perspective view of the conventional floppy disk drive, and FIG. 10 is a perspective view of the conventional floppy disk drive from which an upper cover has been removed. FIG. 11 is a side view of the conventional floppy disk drive, and FIG. 12 is a cross sectional view which shows the mutual relations among a frame, the upper cover and a lower cover of the conventional floppy disk drive.
A floppy disk which has been inserted into the disk drive is held on a disk table in a state that an rotational shaft of the disk table and a center of the disk are aligned with each other. The disk table 11 is rotationally driven by a spindle motor 30 which is provided on a concave portion of the frame 13, thereby the floppy disk is rotated. Further, on the lower surface of the frame 13, a printed circuit board on which many electronic components and parts are mounted is provided.
The floppy disk drive further includes a pair of upper and lower magnetic heads 14 for writing and reading data to and from a floppy disk (note that, only the upper magnetic head is illustrated). These magnetic heads 14 are respectively held on tip portions of a pair of arms of a carriage assembly 15. The tip portions of the arms of the carriage assembly 15 are positioned at both sides of the floppy disk so that the magnetic heads 14 are positioned at the both upper and lower sides of the floppy disk, respectively. The carriage assembly 15 is movably arranged on the frame 13 at the rear side thereof so that the magnetic heads 14 provided on the tip portions of the carriage assembly 15 can move along a predetermined radial direction of a floppy disk (that is, the direction shown by the arrow D in FIG. 10).
A guide rod 17 is arranged on the frame 13 in parallel with the predetermined direction D so that the carriage assembly 15 is guided on the guide road 17. A stepping motor 16 is mounted on a rear frame plate 131 of the frame 13. The stepping motor 16 drives the carriage assembly 15 linearly through the guide rod 17 along the predetermined radial direction D. Specifically, when a lead screw of the stepping motor 16 rotates, a pin attached to the carriage assembly 15 is moved along a helical groove of the lead screw, so that the carriage assembly 15 is moved in the predetermined radial direction D along the guide rod 17.
A flexible print cable (FPC) 152 extends from the carriage assembly 15 in the direction of the guide rod 17, and the tip part of the FPC 152 is electrically connected to a part of the printed wire board 12 provided on the lower surface of the frame 13.
The floppy disk drive further includes an eject plate 21 and a disk holder 22. The frame 13, the eject plate 21 and the disk holder 22 are respectively formed from metal plates which have been subjected to various processes such as a punching process, a press process and a bending process and the like.
Next, with reference to FIG. 11 and FIG. 12, a description will be made with regard to the mutual relations among the frame 13, the upper cover 31 and the lower cover 32.
The upper cover 31 and the lower cover 32 form a casing which covers the frame 13. The upper cover 31 covers an upper side of the frame 13, and the lower cover 32 covers a lower side of the frame 13. The upper cover 31 includes a substantially rectangular top plate 310 and two side plates 311 which are formed by bending the left and right sides of the top plate 310 downwardly, respectively, so that the upper cover 31 has a substantially inverted U-shaped cross section when viewed from the front side of the disk drive. The lower cover 32 includes a substantially rectangular bottom plate 320 and two side plates 321 which are formed by bending the left and right sides of the bottom plate 320 upwardly, respectively, so that the lower cover 32 has a substantially U-shaped cross section when viewed from the front side of the disk drive. When the upper cover 31 and the lower cover 32 are assembled with the frame 13, the side plates 311 of the upper cover 31 and the side plates 321 of the lower cover 32 are arranged on the outer surfaces of the side walls 135 of the frame 13, respectively, so that each of the lower edges 312 of the side plates 311 faces each of the upper edges 322 of the side plate 321 at a roughly middle portion of each side wall 135 to form a substantially continuous outer side surface. Further, since the upper edges 136 of the side walls 135 of the frame 13 are in abutment with the lower surface 313 of the top plate 310 of the upper cover 31, the upper cover 31 is positioned with respect to the frame 13 when assembled. When the floppy disk drive having the casing described above is mounted in a predetermined slot (that is, one inch bay slot) of a computer, the casing is designed so as to have a predetermined size that allows the floppy disk drive to be mounted in the slot.
As described above, in the conventional floppy disk drive, the positioning of the upper cover 31 with respect to the frame 13 when assembling the disk drive is carried out by the abutment of the lower surface 313 of the upper cover 31 against the upper edges 136 of the side walls 135 of the frame 13. Therefore, the side walls 135 of the frame 13 are required to have a predetermined height (see “h1” in FIG. 12) for positioning the upper cover 31 with respect to the frame 13. This means that the side walls 135 of the frame 13 have to have a large size for securing the height h1, which results in a problem in that a large amount of a material (that is, a material for a metal plate) is necessarily required.
Further, the side walls 134 of the frame 13 are also required to have a sufficient mechanical strength against a load applied to the side portions of the casing. Therefore, if the height of the side walls 135 is simply reduced, there arises a problem in that the mechanical strength at the side portions of the disk drive is lowered.